If Autoupdate.autoupdateVersion is set outside of the Autoupdate
package, we wouldn't notify the client of the new version. This
patch simplifies the updating logic by only having one document
per version type.
Regression introduced by the CSS watching code (specifically, f230eba62)
by the sourceIsWatched check. We need to be able to tell the difference
between "source handler didn't do anything because there was an error"
and "source handler didn't do anything because it's web-specific and
this is an os arch".
A simple fix would have been to interpret compileStep.error as
"sourceIsWatched = true", but I didn't think of that until after doing
it the slightly more complicated but more precise way :)
Also, ensure that if the runner rebuilds the client and there's an
error, it properly kills the app process (and the watchers and the
keepalive interval, etc).
presumably this was previously tested on a checkout where
tools/tests/apps/hot-code-push-test/client existed, but git doesn't know
how to check in empty directories. (another alternative would be to
check in a dummy file in that directory)
